A source said: "They really tried to make the marriage work, but sometimes it's best to not be married. They know that about each other now.

"They have worked really hard for a year or more, going to therapy, trying to make it work - and she's been more honest than ever about how hard marriage is - but they just decided it was best to not be together anymore as a couple."

(Photo: Goop.com)

Despite the news, the Iron Man star was seen out publicly with the Coldplay frontman several times earlier this year and they even sang together at a recent charity event in aid of their children's Los Angeles school, performing Cruisin, her song with Huey Lewis in 2000 movie Duets.

A source told Us Weekly magazine: "She called the event chair to say she'd like to sing with Chris."

Insiders insist the pair have always put their children first and present a united front for the sake of their family.

One source told People magazine: "They made an effort to be there for their kids at their activities, and though they had killer schedules they were always around together in L.A. and a united front at parties in their Brentwood neighborhood.

"They weren't a traditional couple per se, but they were a couple and tried to do anything any family would do, from carpool to a lemonade stand.

"They are still a family. They will always be a family. Nothing will ever change that."